A liquid pick-up head or describe above is disclosed in German specification 1503858, in which the suction hose is connected to the in-use upper end of the collection container, and a which the interior of the container communicates with a suction chamber by way of a tube of generally inverted J-shape so arranged that liquid picked up by the application of suction to the suction chamber travels upwardly along the longer limb of the tube and is discharged downwardly from the shorter limb of the tube adjacent to a side wall of the collection container.
Such an arrangement does not afford very efficient separation of entrained liquid droplets, and accordingly significant quantities of moisture may be drawn through the suction hose and into the vacuum cleaner, with possible deleterious effect.
According to the invention, we provide a pick-up head for use with a vacuum cleaner and comprising a hollow body defining a collection container to receive and collect liquid, an outlet leading from the container and including a connector for connection to a source of suction, and a pickup inlet for application to a surface from which liquid is to be picked up. Upstream of the outlet the collection container has an air outlet opening which comprises a flow-restricting orifice having a cross-sectional area which is significantly less than that of the outlet.
Conveniently, an air expansion chamber is provided between the orifice and the outlet.
Preferably, the flow-restricting orifice is disposed adjacent to a side wall of the collection container, at or near the in-use upper end of the container.
According to a particularly preferred feature of the invention, adjacent the flow-restricting orifice there is provided a vortex chamber which includes a curved wall forming a concave air-flow directing surface which extends across the collection container from a position adjacent to a side wall thereof opposite to the side wall at which the flow-restricting orifice is provided a position adjacent the orifice and such that air-flow off the concave surface is directed generally away from the orifice and is required to undergo a reversal of direction to enter the orifice.
The expansion chamber may be in part defined by the curved wall.
A filter element is preferably provided between the orifice and the outlet.
The pick-up inlet may be in the form of an elongated slot which extends between lateral side walls of the collection chamber, preferably at a position adjacent the side wall at which the orifice is provided, and a suction duct may extend from the slot to a discharge outlet which is disposed within the collection container at a position between the slot and the orifice.
In accordance with a further preferred feature of the invention, the discharge outlet is arranged adjacent the side wall of the collection container at which the orifice is provided, and is arranged to face the orifice, an air-flow reversing deflector being disposed between the discharge outlet and the orifice, whereby air-flow from the suction duct undergoes a reversal of direction and enters the collection container flowing in a direction away from the orifice and at a position spaced from the wails of the container.